The invention relates to a method of feeding welding wire from a wire supply reel to a welding torch and devices for carrying out the method.
A method and device for feeding a welding wire are already known from patent specification DE 197 32 379 C2, in which the welding wire is fed from a wire supply reel to a welding device, in particular a welding torch, welding wire feeders being assigned respectively to the wire supply reel and the welding torch, in particular an auxiliary device and a main drive, in which fluctuations in force and a feed pressure or a pressure force are compensated and limited. The force fluctuation and the feed pressure or pressure force is compensated and limited within the auxiliary drive by means of an elastically deformable element and the element, which drives the wire without any slip, is arranged between the drive motor and the drive element.
The disadvantage of this system is that the elastically deformable element is linked to the drive motor, so that the rotary motion directly affects the element.
Another device for feeding a welding wire from a wire supply reel to a welding torch is known from patent specification DE 43 20 405 C2, in which the welding torch and the reel of wire are each assigned a wire feeder device, in particular a main drive and an auxiliary drive. A wire wheel unit is arranged between the wire reel and the welding torch, having means for detecting the bending behaviour of the welding wire, this means being provided in the form of a contactless sensor. The sensor signals of the sensor are applied to a control system, which activates the welding wire feeder devices so that a closed wire loop is formed inside the wire wheel unit.
The disadvantage of this system is that a wire wheel unit of this type in which the welding wire forms a wire loop takes up a lot of space.
A device for feeding a welding wire from a wire reel to a welding torch is known from patent specification U.S. Pat. No. 1,927,896 A, in which the welding torch and the wire reel are each assigned a wire feeder device. The welding device is fed from the wire reel to the welding torch along a curved path. To this end, the bending behaviour is measured via a spring-mounted roller, which is applied directly against the welding wire. If tension in the welding wire increases, the roller is deflected downwards so that a contact arm or lever fixed to the roller modifies a controllable resistance. This resistance is linked to the welding wire feeder co-operating with the wire reel, which enables a correction to be applied on the basis of the bending behaviour of the welding wire.
The disadvantage of this system is that fluctuations in the feed to the welding torch affect the control circuit and it can therefore only be used in stationary welding systems unless the configuration of the welding torch is modified.
A welding system is disclosed in patent specification JP 08-309 536 A, in which the welding wire is delivered to a welding torch via a hose pack.
The underlying objective of the invention is to propose a method and a device for feeding welding wire from a wire supply reel to a welding torch and a wire feeder system for feeding and monitoring a welding wire from a wire feel to a welding torch, by means of which the welding wire can be fed slip-free and several welding wire feeder devices used in a welding system can be reliably and simply controlled.
This objective is achieved according to one aspect of the invention due with a method of monitoring the feed force on a welding wire as the welding wire is fed from a sire supply reel to a welding torch, the feed force being supplied by at least one welding wire feeder and another welding wire feeder for applying the feed force acting on the wire in a feed direction and the feed force is detected directly in a wire feed between the at least one welding wire feeder and the other welding wire feeder. This method is characterised in that a displacement of the welding wire transversely to the feed direction caused by the feed force is detected in a tubular sensor between the at least one welding wire feeder and the other welding wire feeder, the feed force or rate of the at least one welding wire feeder or the other welding wire feeder is varied in dependence on the extent of the transverse displacement with the interior of the tubular sensor and the welding wire is deflected by a baffle system in the interior of the tubular sensor from a centered rectilinear position in a predetermined direction whereby the direction of reflection of the welding wire is automatically determined when the required feed force is exceeded.
The advantage of this method is that by using a tubular sensor, the feed pressure and the pressure force of the welding wire can be simply monitored by detecting a short circuit of the welding wire with the housing of the sensor. Another advantage resides in the fact that monitoring the feeder pressure in the feed direction of the welding wire in this manner does not require allowance to be made for other effects on the welding wire, as is the case with the prior art. It is inexpensive to manufacture the sensor in a tube design because no electronic components or moving parts are needed for a sensor of this type.
Other advantageous features are described in the claims. The resultant advantages may be found in the description.
The objective is also achieved according to another aspect of the invention with a device for monitoring a feed force on a welding wire as the welding wire is fed from a wire supply reel to a welding torch, comprising a first welding wire feeder associated with the wire supply reel and another welding wire feeder associated with the welding torch for enhancing the feed force, a tubular sensor arranged between the first welding wire feeder and the other welding wire feeder to detect a fluctuation in the feed force, the wire being fed from the wire supply reel to the welding torch via a hose sack or a guide system, the tubular sensor serving to detect a deflection of the welding wire away from the feed direction in the interior of the tubular sensor, and a baffle system in a housing of the tubular sensor for deflecting the welding wire from a centered rectilinear position in a predetermined direction whereby the direction of deflection of the welding wire is automatically determined when the required feed force is exceeded.
The advantage of this approach is that the most varied range of welding wires can be used and no adjustments or modifications of any kind are needed to detect the feed pressure and the pressure force of the welding wire because the system automatically adjusts to natural stiffness of the respective welding wire. This is possible in particular because of the natural stiffness if the welding wire is exceeded by the feed pressure, the welding wire is deflected and the feed pressure is reduced or compensated by an adjustment to the welding wire feed rate prompted by the short circuit with the housing of the tubular sensor so that the system of welding wire feeders is automatically adjusted to the natural stiffness of the welding wire.
Other advantageous embodiments are described in the claims. The resultant advantages may be found in the description.
Other advantageous embodiments are described in the claims. The resultant advantages may be found in the description.
The objective of the invention is also achieved with a device for welding wire from a wire supply reel to a welding torch, comprising a first welding wire feeder and another welding wire feeder assigned to the wire supply reel provided in the form of a welding wire roller, the wire being fed from the wire supply reel to the welding torch via a hose pack or a guide system, in particular a tube provided in the hose pack or in the guide system, and a wire wheel unit in which the welding wire runs in a looping shape is disposed before the point at which the welding wire enters the hose pack or the guide system, a detection means, in particular a sensor, being assigned to the welding wire in the wire wheel unit to detect the bending behaviour of the welding wire, characterised in that the wire supply reel is disposed so as to rotate at the center of the loop-shared path of the welding wire in the wire wheel unit, the detection means being an angle sensor or a rheostat and the detection means is applied via a rigid lever attached thereto to the welding wire in the wire wheel unit and the detection means is connected to a controller unit for the welding wire feeder and/or the apparatus, in particular the other welder wire feeder. The advantage of this approach is that with a wheel of this type, the feed movements of the welding wire are picked up and absorbed by the wire wheel, thereby providing a simple means of regulating and controlling the welding wire feeder system.
The objective of the invention is also achieved by the characterising features of claims 38 and 39.